[IPOL discuss] Unable to build IPOL demo due to libraries' link order problem in some source codes

[Miguel Colom]

Quoting Jacques Froment <Jacques.Froment at univ-ubs.fr>:

> I am surprised to be the first user who raises the issue of the  
> libraries' link
> order, since Ubuntu is considered to be the most well-known  
> distribution in the Linux world.

Indeed, I use Ubuntu with gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1)  
and I check one by one each C++ code before they're uploaded to  
production.

I've tried to compile one of the C++ codes that are supposed to don't  
compile and it couldn't be compiled now in my machine. Actually, I  
didn't check all codes, since I wasn't assigned the task of taking  
care of the demo system from the beginning.

That demo, for example, fails to compile in my Ubuntu:

[...]
(...).o: En la función `(...)':
(...).c:(.text+0xc4): referencia a `sqrt' sin definir
(...).o: En la función `(...)':
(...).c:(.text+0x71): referencia a `sqrt' sin definir
(...).o: En la función `main':
(...).c:(.text.startup+0x15f): referencia a `floor' sin definir
(...): error: ld returned 1 exit status
make: *** [(...)] Error 1

This code compiles well in production, however.
In production, we're using gcc version 4.4.5 (Debian 4.4.5-8).

> Anyway, I think that the only way to solve this problem (as well as  
> the following
> that are sure to come), is that the IPOL staff checks IPOL codes on  
> different Linux
> distributions, starting with the most common: Ubuntu.
> Of course you will understand that if I am willing to help report an  
> error, I can not
> substitute myself for the IPOL team to exhaustively check all  
> published (as well as
> submitted) IPOL codes.

I agree. A possible solution is to create a Python script that  
compiles the sources one by one following the instructions in the  
build() function and check afterwards that the binaries are created.

Also, thanks a lot for your detailed review of the other codes.
Indeed, this problem is serious, since many demos may stop working  
only after a compiler update and recompilation. And lots of users may  
be unable to compile the sources (as it is happening now).

We'll give priority to this problem.

Best,
Miguel